This present invention relates to the design and method of production associated with a pipe flange connection for the pressurized transport of abrasive and/or corrosive materials. The pipe flange connection has an interior lining which does not bulge inwardly when the pipe flange is mated to another object using compressive force and provides for high pressure sealing capability with complete isolation of a mechanical joint from abrasive and/or corrosive materials.
The use of piping lined internally with abrasion resistant and/or chemically resistant materials, e.g. elastomers and plastics, to facilitate the transport of abrasive and/or corrosive materials in the form of a liquid, liquid/solid slurry mixture, or as a dry powder is well known. When piping is assembled in various configurations, pipe flanges having an inside lining are designed and constructed in accordance with established national standards. The existing pipe flange connections contain design flaws which limit their application in pressurized applications and limit the life expectancy of lined piping systems. Specifically, known designs are limited in terms of pressure rating and the maintenance of pressure tightness over the service life of the pipe flange connection.
The pressure seal in prior art pipe flange connections was accomplished by extending an internal lining across the faces of the flange. This extension of the internal lining provided a pressure sealing gasket surface as well as a mechanically fixing the lining to the ends of the pipe. In addition, the remainder of the pipe flange was isolated from corrosive and/or abrasive attack. As shown in FIG. 1, compressing the lining in this manner resulted in compression and extrusion of the lining so that a visible inward bulging of lining material occurred at the parting line of the joint located between the objects being mated together. This inward bulge causes and/or contributes to flow turbulence Q at the joint interface. Turbulence of this type increases the rate of wear and corrosion of protective liners.
Known pipe flange connections are also limited in the internal pressure that can be contained by such connections. This limitation is due to the inherent low strength of the lining which serves as the gasket for the joint. Linings have a tendency to creep or continue to deform under the constant stress imposed when opposing flange faces are compressed together. Gasket creep will cause gaskets to loose their sealing ability with time compromising the pressure integrity of the joint. Compression limiting stops are often used within pipe flange connections to mitigate the affects of gasket creep but do nothing to improve the basic pressure retention capability of the lining when used as a gasket.
While conventional pipe flanges are generally effective for supplying fluid, for the foregoing reasons, a need exists for a pipe flange connection for the pressurized transport of abrasive and/or corrosive materials.